Method for preparing graphite film

Abstract

A method for preparing a graphite film includes steps of preparing a carbonized frame carbonized at a temperature Ta, and an aromatic polyimide film or a carbonized film of the aromatic polyimide film carbonized at a temperature Tb, assembling the carbonized frame and the aromatic polyimide film or the carbonized film of the aromatic polyimide film into an intermediary body 1 , carbonizing the intermediary body 1 at a temperature Td to produce a carbonized intermediary body, and graphitizing the carbonized intermediary body to produce the graphite film. The temperature Ta is larger than the temperature Tb and the temperature Tb is smaller than the temperature Td. The graphite film has a surface roughness expressed as an arithmetic mean height Sa of less than 18 nm, a thickness of 5 nm or more and less than 10 μm, and an area of 1.0 cm 2 or more and less than 500 cm 2 .

The invention claimed is: 
     
       1. A method for preparing a graphite film comprising steps of:
 preparing a carbonized frame carbonized at a temperature Ta, and an aromatic polyimide film or a carbonized film of the aromatic polyimide film carbonized at a temperature Tb, 
 assembling the carbonized frame and the aromatic polyimide film or the carbonized film of the aromatic polyimide film into an intermediary body  1 , 
 carbonizing the intermediary body  1  at a temperature Td to produce a carbonized intermediary body, and 
 graphitizing the carbonized intermediary body to produce the graphite film, 
 wherein:
 the temperature Ta is larger than the temperature Tb and the temperature Tb is smaller than the temperature Td, and 
 the graphite film has a surface roughness expressed as an arithmetic mean height Sa of less than 18 nm, a thickness of 5 nm or more and less than 10 μm, and an area of 1.0 cm 2  or more and less than 500 cm 2 . 
 
 
     
     
       2. The method according to  claim 1 , wherein the aromatic polyimide film has a thickness of 10 nm or more and less than 20 μm. 
     
     
       3. The method according to  claim 2 , wherein the temperature Ta for carbonization is 500° C. or higher and lower than 2000° C. 
     
     
       4. The method according to  claim 2 , wherein the graphite film has an electrical conductivity of 8000 S/cm or more and 26000 S/cm or less in a film direction. 
     
     
       5. The method according to  claim 2 , wherein the carbonized frame is obtained by carbonizing the aromatic polyimide film having a thickness of 10 to 100 μm in an inert gas. 
     
     
       6. The method according to  claim 2 , wherein the intermediary body  1  is carbonized or graphitized with applying a load to the carbonized frame. 
     
     
       7. The method according to  claim 2 , wherein the carbonized frame extends after the graphitization, compared with the carbonized frame before the graphitization. 
     
     
       8. The method according to  claim 1 , wherein the temperature Ta for carbonization is 500° C. or higher and lower than 2000° C. 
     
     
       9. The method according to  claim 1 , wherein the graphite film has an electrical conductivity of 8000 S/cm or more and 26000 S/cm or less in a film direction. 
     
     
       10. The method according to  claim 1 , wherein the carbonized frame is obtained by carbonizing the aromatic polyimide film having a thickness of 10 to 100 μm in an inert gas. 
     
     
       11. The method according to  claim 1 , wherein the intermediary body  1  or an intermediary body  2  is carbonized or graphitized with applying a load to the carbonized frame. 
     
     
       12. The method according to  claim 1 , wherein the carbonized frame extends after the graphitization, compared with the carbonized frame before the graphitization. 
     
     
       13. A method for preparing a graphite film comprising steps of:
 preparing a carbonized frame carbonized at a temperature Ta and a graphitized film graphitized at a temperature Tc, 
 assembling the carbonized frame and the graphitized film into an intermediary body  2 , and 
 graphitizing the intermediary body  2  at a temperature Te to produce the graphite film, 
 wherein:
 the temperature Tc is smaller than the temperature Te, and 
 the graphite film has a surface roughness expressed as an arithmetic mean height Sa of less than 18 nm, a thickness of 5 nm or more and less than 10 μm, and an area of 1.0 cm 2  or more and less than 500 cm 2 . 
 
 
     
     
       14. The method according to  claim 13 , wherein the temperature Tc for the graphitization is 2000° C. or higher and 2800° C. or lower. 
     
     
       15. The method according to  claim 1 , wherein the intermediary body  2  is carbonized or graphitized with applying a load to the carbonized frame. 
     
     
       16. The method according to  claim 14 , wherein the carbonized frame extends after the graphitization, compared with the carbonized frame before the graphitization. 
     
     
       17. The method according to  claim 13 , wherein the graphite film has an electrical conductivity of 8000 S/cm or more and 26000 S/cm or less in a film direction. 
     
     
       18. The method according to  claim 13 , wherein the carbonized frame is obtained by carbonizing an aromatic polyimide film having a thickness of 10 to 100 μm in an inert gas. 
     
     
       19. The method according to  claim 13 , wherein the intermediary body  2  is carbonized or graphitized with applying a load to the carbonized frame. 
     
     
       20. The method according to  claim 13 , wherein the carbonized frame extends after the graphitization, compared with the carbonized frame before the graphitization.